浅埋偏压铁路隧道爆破施工中的超挖控制与优化
袁枫杰1王昊乾1宋官平1袁浪1高航1徐前卫2
Construction Optimization of Shallow Railway Tunnels under Unsymmetrical Pressure for Reducing Blasting Over-excavation
YUAN Fengjie1WANG Haoqian1SONG Guanping1YUAN Lang1GAO Hang1XU Qianwei2
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作者信息:1.中铁二局第五工程有限公司，610031，成都
2.同济大学交通运输工程学院，200092，上海
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Affiliation:1.The Fifth Company of China Railway 2nd Bureau Group 610031, Chengdu， China
2.School of Transportation Engineering, Tongji University， 200092, Shanghai, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2024.06.043
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中图分类号/CLCN:U455.6
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栏目/Col:施工技术
摘要:
［目的］隧道施工的超挖现象会影响隧道开挖的顺利进行与安全性，并且增加施工成本并降低经济效益。隧道施工超挖主要是由爆破施工不合理导致的。为了在根本上解决超挖问题，须对爆破设计及爆破施工工艺进行研究并优化。［方法］结合重庆铁路枢纽东环线(重庆东环线铁路)浅埋偏压上下交叠铁路隧道工程，通过理论分析和现代计算机技术，分析了拱顶、拱腰和拱脚超挖现象的原因，对钻孔位置进行动态优化设计，提出了超挖控制措施和解决方案。［结果及结论］隧道拱顶处的超挖主要由于爆破后机械开挖对破碎区围岩的二次扰动导致，拱腰和拱脚的超挖主要由爆破用药量及钻眼施工的不恰当引起。不仅如此，节理裂隙的存在，也会导致围岩强度大幅降低。因此，应在拱顶处适当爆破欠挖，以降低对围岩的扰动，后续再配合人工和机械开挖修边，进而降低超挖量。其次，根据围岩属性，并基于GA-SVR模型与遗传算法，对炮眼间距进行合理优化。现场监测结果表明，在未采用最优炮眼间距的初始阶段节理发育地层，开挖产生的超挖量约为40 cm，而采用最优炮眼间距后，该超挖量降至9 cm左右，说明设计间距的优化能有效控制隧道超挖。上述成果可为类似工程提供借鉴和参考。
Abstracts:
［Objective］ Over-excavation in tunnel construction, mainly caused by inappropriate blasting, will affect the smooth progress and safety of tunnel excavation, increase construction cost and reduce economic benefits. In order to radically solve this problem, blasting design and blasting construction technology should be studied and optimized. ［Method］ Based on the shallow buried unsymmetrical pressured layered railway tunnel project for Chongqing Railway Hub East Ring Line (Chongqing East Ring Railway) ,the causes of vault, arch haunch and arch foot over-excavation are analyzed with theoretical method and modern computer technology. The drilling positions are designed with dynamic optimization, and control measures and solutions for over-excavation are put forward. ［Result & Conclusion］ Over-excavation at the tunnel vault is mainly caused by the secondary disturbance of the surrounding rock in smashed area by mechanical excavation after blasting, and over-excavation at the arch waist and arch foot is mainly caused by the improper amount of blasting explosive and improper drilling. In addition, the existence of rock cracks will also lead to significant decrease of the surrounding rock strength. Therefore, proper blasting and under-excavation should be done at the vault to reduce the disturbance of the surrounding rock, and then manual + mechanical excavation and trimming should be combined to reduce the amount of over-excavation.Secondly, according to the attributes of surrounding rock, and based on GA-SVR model and genetic algorithm, the blasthole spacing is properly optimized.On-site monitoring results show that in the initial stage without optimized blast hole spacing, the over-excavation in cracked stratum is about 40cm, which is reduced to about 9cm after the blast hole spacing optimization. The results indicate that optimizing the blast hole spacing can effectively control tunnel over-excavation. The above results can provide reference for similar projects.
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